This invention relates to a spray header and nozzle assembly useful, for example, in drum granulation apparatuses.
Granulation drums, such as those described in U.S. Pat. Nos. 3,877,415 and 3,991,225 issued to Bloulin are used in various industrial processes such as for the production of urea. Granulation of urea using the rotary drum granulation process is also described in U.S. Pat. Nos. 4,213,924; 4,424,176 and 4,506,453.
In the drum granulation process a spray header and nozzle assembly is used to spray molten product onto a falling curtain of small seed particles and undersize recycle granules to increase the particle size by successive coats of molten material. A recurring problem with the use of the prior art spray headers and nozzles has been with plugging of the nozzle orifice because the molten product solidifies before it is ejected from the nozzle. It is important to maintain the product in a molten state until it is ejected from the nozzle and onto the falling curtain to avoid the plugging of the nozzle orifices.
Heretofore, spray headers had nozzles extending out from the spray header. Oftentimes dust particles of material being sprayed would contact the nozzle extensions and melt on the surface thereof and, when cooled, would solidify and plug the nozzles. In addition, the extended nozzles were cooled by air currents inside the drum thereby freezing molten material inside the nozzle.
It is therefore, desired to provide a spray header and nozzle assembly that substantially eliminates the plugging problems of the prior art spray devices.